Videoconferencing uses telecommunications of audio and video to bring people at different sites together for a meeting. This can be as simple as a conversation between two people in private offices (point-to-point) or involve several sites (multipoint) with more than one person in a number of rooms at different sites. Besides the audio and visual transmission of people, videoconferencing can be used to share documents, computer-displayed information, and whiteboards.
Videoconferencing among multiple remote points is sometimes facilitated employing Multipoint Control Unit (MCU) for routing Audio and Video streams, sometimes also called an Audio/Video MCU (AVMCU). An MCU is a bridge that interconnects calls from several sources. All parties call the MCU, or the MCU may call the parties which are going to participate, for initiating the conference. MCUs may use various protocols such as Internet Protocol (IP), and be structured as software program(s), hardware, or combination of the two. One of the main tasks for an MCU is to organize the conference based on capabilities of the participating parties (e.g. receiving parties and source in a single source directed conference).
In video conferencing, users may desire to see multiple meeting participants at same time. A typical video conference solution transcodes and reconstructs a multi-person view on the AVMCU into one video stream. Another approach is to forwarding multiple streams from different senders to one user. Former case is simple but not scalable. Latter case scales better, but is more complex.